View full sizeRobin Conn / The Huntsville TimesCrews get ready to repair a sink hole on I-65 about 2 miles of north of the Hartsellle exit.View full sizeRobin Conn / The Huntsville TimesTraffic exits I-65 at exit 318 for a detour north on U.S. Highway 31.

WATCHING TRAFFIC ON U.S. 31 - Edith Bennich rocked back and forth in her rocking chair Thursday afternoon, watching the traffic out her window in Hartselle go from slow to slower to stop.

"Honey," Bennich said, "we don't see traffic like this here."

A sinkhole near mile marker 328 on Interstate 65 shut down the northbound lanes Thursday. Department of Transportation crews are now making repairs to the road, which could force traffic to be routed away from I-65 for perhaps a month, according to DOT engineer Johnny Harris.

"Best-case scenario, we're talking about three or four days," Harris said. "Worst case, you could be talking about three or four weeks. We don't really know how blessed we're going to be."

Harris said the DOT expected to have a better idea of the timetable today based on investigation of the sinkhole. Work to determine its cause began around noon Thursday after northbound traffic was stopped.

"I wouldn't liken it to a dentist filling a cavity, but that's basically what you do," Harris said. "We'll put some material in there to fill up the bad spot, cover it back up and restore (the road)."

Traffic along U.S. 31 worsened as the day wore on, the inevitable result of more and more cars getting caught in the detour's web. At midday, it took about an hour to travel the detour's route. State troopers said 16 miles of I-65 northbound are closed - a span that would normally be driven in 12-15 minutes.

Bennich watched in amazement as the traffic backed up in front of her business, B&G OK Tires. "If it brings in business," she said, "I like it."

Then again, maybe not.

"It's a pain in the neck," Bennich said. "It really is. It's a pain."

Hoping to alleviate that congestion, officials announced Thursday afternoon that motorists in light vehicles could travel as far north as the Thompson Road exit in Hartselle before leaving the interstate.

But heavy trucks would still be required to exit in Lacon, which is where all traffic was rerouted Thursday. Traffic was backed up on I-65 more than two miles at midday at the Lacon exit.

"It was not too bad," said a woman from Auburn who declined to give her name. "We slowed down a little in the small towns. But it was not too bad."

Motorists drove through the sleepy town of Falkville and the Morgan County countryside before reaching Hartselle and its series of stoplights that ground traffic to a halt. At the Dairy Queen in Hartselle, dogs were walked in a vacant adjacent lot and cars with tags from Kentucky, Texas, Michigan, Tennessee and Oregon were spotted in the parking lot.

The detour continued to Decatur, forcing interstate travelers to encounter one of the city's busiest intersections at Sixth Avenue and Beltline Road.

John Lumkes was traveling with his family from a vacation in Gulf Shores back home to Lafayette, Ind. He said their estimated time of arrival at home was 10 p.m. "We're going to be a little later than that now," he said.

Lumkes said he wasn't even aware of the problem, only that throughout the detour his GPS kept telling him to turn right - back toward the interstate.

"At first, I was looking forward to seeing some of the Alabama countryside," Lumkes said.

But as his family was loading back in the car, though, Lumkes could only say, "I'm glad we're through it."